Exemestane
Exemestane is an aromatase inhibitor (a hormone-lowering medicine) used to treat estrogen-receptor positive early breast cancer and advanced breast cancer in postmenopausal women after tamoxifen.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 11 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Exemestane (Aromasin) is a hormone-lowering breast cancer medicine that permanently disables aromatase, the enzyme postmenopausal women rely on for most of their estrogen. On the market since about 1999 and available as a generic, it is used after tamoxifen, either to finish five years of hormone therapy for early estrogen-receptor positive cancer or to treat advanced cancer that has progressed. Most women tolerate it reasonably well, but hot flushes, tiredness and achy joints are common enough to expect. The one thing to stay on top of is bone thinning, so expect a bone density scan and vitamin D check early on, and report bone pain or any fracture.
Clinical pearls
- Take it after a meal each day, since food helps your body absorb exemestane.
- St. John’s wort, rifampin, phenytoin, carbamazepine and phenobarbital can lower exemestane levels, so your prescriber may need to adjust the dose.
- Avoid estrogen-containing medicines that work throughout the body, such as hormone replacement therapy, because they work against exemestane.
- If pregnancy is possible, use effective birth control during treatment and for one month after the last dose.
Patient information guide A plain-language walkthrough of Exemestane, written from its FDA label.
What Exemestane is used for
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Exemestane is used in postmenopausal women for two breast cancer situations.
- Early breast cancer that is estrogen-receptor positive, after two to three years of tamoxifen, to complete five consecutive years of hormone therapy (Aromasin and exemestane tablets).
- Advanced breast cancer that has progressed after tamoxifen (Aromasin and exemestane tablets).
How Exemestane works
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Breast cancer cells can depend on estrogen to grow. After menopause, the body still makes estrogen by using the aromatase enzyme to convert other hormones. Exemestane looks like the natural hormone that enzyme uses. The enzyme processes it and becomes permanently disabled.
The result is much lower estrogen in the blood. Exemestane did not affect cortisol or aldosterone production.
Exemestane dosage
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Exemestane is taken by mouth as a tablet, once a day, after a meal. Aromasin and exemestane tablets share this schedule.
- Take it at about the same time each day.
- If you take a strong CYP 3A4 inducer, your prescriber may raise your dose.
- Follow your prescriber and the label for the exact dose.
Dosing details from the FDA-approved label
From the Exemestane prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Adjuvant treatment of postmenopausal women with estrogen-receptor positive early breast cancer who have received two to three years of tamoxifen and are switched to exemestane for completion of a total of five consecutive years of adjuvant hormonal therapy
- One 25 mg tablet once daily after a meal
- Taken after a meal
- Treatment of advanced breast cancer in postmenopausal women whose disease has progressed following tamoxifen therapy
- One 25 mg tablet once daily after a meal
- Taken after a meal
- Patients receiving exemestane with a strong CYP 3A4 inducer such as rifampicin or phenytoin
- 50 mg once daily after a meal
- Taken after a meal
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION Recommended Dose: One 25 mg tablet once daily after a meal ( 2.1 ). 2.1 Recommended Dose The recommended dose of exemestane tablet in early and advanced breast cancer is one 25 mg tablet once daily after a meal. adjuvant treatment of postmenopausal women with estrogen-receptor positive early breast cancer who have received two to three years of tamoxifen and are switched to exemestane tablets for completion of a total of five consecutive years of adjuvant hormonal therapy. the treatment of advanced breast cancer in postmenopausal women whose disease has progressed following tamoxifen therapy. 2.2 Dose Modifications Concomitant use of strong CYP 3A4 inducers decreases exemestane exposure. For patients receiving exemestane tablets with a strong CYP 3A4 inducer such as rifampicin or phenytoin, the recommended dose of exemestane tablet is 50 mg once daily after a meal [see Drug Interactions ( 7 ) and Clinical Pharmacology ( 12.3 )].
Read the full Dosage and Administration section on DailyMed →
Exemestane side effects
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Most side effects in studies were mild to moderate. Common ones include:
Common side effects
- Hot flushes
- Tiredness (fatigue)
- Joint pain (arthralgia)
- Headache
- Trouble sleeping (insomnia)
- Increased sweating
- Nausea
- Dizziness
When to get medical help
- Call your doctor if you have chest pain, which may signal heart problems. Heart-related events, including heart attack and heart failure, were reported more often with exemestane than with tamoxifen in studies.
- Call your doctor about bone pain or a fracture. Exemestane can reduce bone density over time.
- Call your doctor if you notice signs of liver problems. Hepatitis has been reported after approval.
- Get help for signs of a severe allergic reaction, such as hives, itching or a widespread rash.
- Tell your doctor right away if you become pregnant or think you might be.
Exemestane warnings and precautions
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- Bone loss: Bone density drops over time. Women with or at risk for osteoporosis should have bone density assessed at the start.
- Vitamin D: Levels should be checked before starting. Deficiency should be treated.
- Pregnancy: It can cause fetal harm. Use effective contraception during treatment and for 1 month after.
- Estrogen products: Avoid systemic estrogen-containing medicines.
- Lab changes: Liver-related tests, bilirubin, creatinine and lymphocyte counts can change.
- Premenopausal women: It is not indicated for them.
Exemestane interactions
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A few things can change how exemestane works.
- Rifampicin, phenytoin, carbamazepine, phenobarbital and St. John's wort can lower exemestane levels, so a dose change may be needed.
- Estrogen-containing medicines that work throughout the body can interfere with its action.
- Ketoconazole did not significantly change exemestane levels.
Interactions listed in the FDA-approved label
From the Exemestane prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Strong CYP 3A4 inducers (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. John's wort): Co-medications that induce CYP 3A4 may significantly decrease exposure to exemestane. Increase the exemestane dose to 50 mg once daily after a meal for patients also receiving a strong CYP 3A4 inducer.
- Rifampicin: In a study of 10 healthy postmenopausal volunteers pretreated with rifampicin 600 mg daily for 14 days followed by a single dose of exemestane 25 mg, the mean plasma Cmax and AUC0-∞ of exemestane were decreased by 41% and 54%, respectively.
- Ketoconazole (potent CYP 3A4 inhibitor): Coadministration has no significant effect on exemestane pharmacokinetics.
- CYP isoenzyme inhibitors: Significant effects on exemestane clearance by CYP isoenzyme inhibitors appear unlikely, although no other formal drug-drug interaction studies with inhibitors have been conducted.
- Major CYP isoenzymes (CYP 1A2, 2C9, 2D6, 2E1, and 3A4): Exemestane does not inhibit any of the major CYP isoenzymes, including CYP 1A2, 2C9, 2D6, 2E1, and 3A4.
Read the label’s full interactions text
7 DRUG INTERACTIONS Strong CYP 3A4 inducers: Concomitant use of strong CYP 3A4 inducers decreases exemestane exposure. Increase the exemestane dose to 50 mg ( 2.2 , 7 ). Drugs That Induce CYP 3A4 Co-medications that induce CYP 3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. John's wort) may significantly decrease exposure to exemestane. Dose modification is recommended for patients who are also receiving a strong CYP 3A4 inducer [see Dosage and Administration (2.2) and Clinical Pharmacology (12.3) ].
Drug Interaction Studies Exemestane does not inhibit any of the major CYP isoenzymes, including CYP 1A2, 2C9, 2D6, 2E1, and 3A4. In a pharmacokinetic interaction study of 10 healthy postmenopausal volunteers pretreated with potent CYP 3A4 inducer rifampicin 600 mg daily for 14 days followed by a single dose of exemestane 25 mg, the mean plasma C max and AUC 0–∞ of exemestane were decreased by 41% and 54%, respectively [see Dosage and Administration (2.2) and Drug Interactions (7) ]. In a clinical pharmacokinetic study, coadministration of ketoconazole, a potent inhibitor of CYP 3A4, has no significant effect on exemestane pharmacokinetics. Although no other formal drug-drug interaction studies with inhibitors have been conducted, significant effects on exemestane clearance by CYP isoenzyme inhibitors appear unlikely.
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Exemestane
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- Do not use if you are allergic to exemestane or any ingredient in it.
- Tell your doctor if you are pregnant, could become pregnant, or are breastfeeding.
- Tell your doctor about osteoporosis or low bone density.
- Safety in children has not been established.
- Liver or kidney impairment raised exemestane levels about 3 times in studies, but the label says a dose adjustment does not appear necessary for liver impairment.
Exemestane overdose
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In studies, very high doses were well tolerated. There is no specific antidote. Treatment is supportive care with monitoring of vital signs. Contact a doctor or poison control if too much is taken.
What Exemestane does in the body
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Exemestane lowers estrogen levels in postmenopausal women. Suppression of 85% to 95% or more was reached at the standard daily dose. Maximum effect after a dose occurs in 2 to 3 days and lasts 4 to 5 days. It did not affect cortisol, aldosterone or thyroid function. HDL (good) cholesterol decreased by 6% to 9%.
How your body processes Exemestane
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Exemestane is absorbed from the gut. A high-fat meal increased the amount absorbed. It is broken down extensively by the liver, mainly by the CYP 3A4 enzyme. Its half-life is about 24 hours. It leaves the body about equally in urine and feces, with less than 1% as unchanged drug in urine.
How to store Exemestane
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Store at 25°C (77ºF); excursions permitted to 15° to 30°C (59° to 86°F) .
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Exemestane
141 supplements and herbal products have documented interactions with Exemestane in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 3
- Moderate · 98
- Minor · 40
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Exemestane: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Exemestane — the kind of thing our pharmacy team would talk through with you at the counter.
What is exemestane for?
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How should I take it?
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What side effects should I expect?
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Does it affect my bones?
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Can I take it with other medicines or supplements?
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What about pregnancy and breastfeeding?
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Is Exemestane available over the counter?
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When was Exemestane first available?
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Who makes Exemestane?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Exemestane on HelloPharmacist
Exemestane forms and strengths (how it comes)
Exemestane is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Exemestane inactive ingredients by manufacturer.
Tablet
How this form is used
- Aromasin and exemestane tablets are used for early breast cancer in postmenopausal women after two to three years of tamoxifen.
- Aromasin and exemestane tablets are used for advanced breast cancer in postmenopausal women after tamoxifen.
- Both are for estrogen-receptor positive early breast cancer in the adjuvant setting.
- Aromasin and exemestane tablets are taken by mouth once daily after a meal.
- Aromasin and exemestane tablets may need a dose change if taken with a strong CYP 3A4 inducer such as rifampicin or phenytoin.
Exemestane on the U.S. market: products, makers and brands
How Exemestane appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
11 companies list 11 Exemestane product records with the FDA, mostly as tablet; the earliest marketing or approval year on record is 1999. Brand names on the directory include Aromasin; the rest are generics.
Also listed with the FDA, not a patient dose form: Powder (14) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
How widely Exemestane is used (Medicaid data)
A general measure of how commonly Exemestane is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Exemestane is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Exemestane prescribed? Of the 1,601 medications we measure, Exemestane ranks #702 by Medicaid prescriptions — more than 56% of them.
Utilization by Exemestane product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
exemestane 25 MG Oral Tablet
Summed across the 8 of 21 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 310261
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Exemestane, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 8 of 21 listed Exemestane NDCs with Medicaid activity.
Compare Exemestane products
A representative set of FDA-listed product records for Exemestane — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 25 mg | Oral | Aurobindo Pharma Limited | ANDA | View NDC → |
| 25 mg | Oral | Breckenridge Pharmaceutical, Inc. | ANDA | View NDC → |
| 25 mg | Oral | Bryant Ranch Prepack | ANDA | View NDC → |
| 25 mg | Oral | Cipla USA Inc. | ANDA | View NDC → |
| 25 mg | Oral | Florida Pharmaceutical Products, LLC | ANDA | View NDC → |
| 25 mg | Oral | Mylan Pharmaceuticals Inc. | NDA AUTHORIZED GENERIC | View NDC → |
| 25 mg | Oral | NorthStar Rx LLC | ANDA | View NDC → |
| 25 mg | Oral | Pharmacia & Upjohn Company LLC | NDA | View NDC → |
| 25 mg | Oral | Upsher-Smith Laboratories, Inc. | ANDA | View NDC → |
| 25 mg | Oral | Zydus Lifesciences Limited | ANDA | View NDC → |
| 25 mg | Oral | Zydus Pharmaceuticals USA Inc. | ANDA | View NDC → |
Showing 11 of 11 products — FDA National Drug Code Directory. See every product, package size and price: browse all 11 Exemestane NDCs →
Exemestane side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Exemestane — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Exemestane in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Exemestane FDA approval history
How Exemestane went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Exemestane recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Exemestane recalls since July 2021.
✅No Exemestane recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 258494 1 dose form · 1 strength
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Dose form (SCDF) Oral Tablet RxCUI 375061In current FDA listingsClinical drug / strength (SCD) 25 MGRxCUI 310261
Look up RxCUI 258494 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Exemestane supply and shortage status
Whether Exemestane is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
💵 What Exemestane costs pharmacies (NADAC benchmark)
The national average invoice price pharmacies pay for the drug itself, from CMS's NADAC survey (data as of Sep 30, 2026). This is a supply-cost benchmark — not a retail price and not what you'd pay at the counter.
| Form | Strength | Pharmacy acquisition benchmark | |
|---|---|---|---|
| Tablet · Oral | 25 mg | $38.98 per tablet | NDC details & price history |
| Tablet, Film Coated · Oral | 25 mg | $0.748 per tablet | NDC details & price history |
| Tablet, Sugar Coated · Oral | 25 mg | $0.748 per tablet | NDC details & price history |
Source: CMS National Average Drug Acquisition Cost (NADAC), a survey of retail pharmacy invoice prices. Benchmarks shown are the range across package sizes of a representative product for each form and strength — other manufacturers' products may differ.
Exemestane brand names
Exemestane is sold under one brand name in the FDA directory — Aromasin. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Exemestane: manufacturers and labelers
11 companies list Exemestane products with the FDA. By number of product records, the largest are Aurobindo Pharma Limited, Breckenridge Pharmaceutical, Inc., Bryant Ranch Prepack. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Exemestane drug class (RxNorm)
Exemestane belongs to the Aromatase Inhibitor class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Exemestane page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Greenstone LLC is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →